Silicon materials are known to be used as components of a semiconductor, a solar battery, a secondary battery, and the like, and research has been actively conducted for silicon materials in recent years.
For example, Non-Patent Literature 1 discloses that CaSi2 is reacted with an acid to synthesize a layered polysilane.
Patent Literature 1 discloses that CaSi2 is reacted with an acid to synthesize a layered polysilane, and also discloses that a lithium ion secondary battery including the layered polysilane as an active material exhibits a suitable capacity.
In addition, Patent Literature 2 discloses an alloy composed of silicon, aluminum, iron, and titanium, and also discloses a lithium ion secondary battery including the alloy as a negative electrode active material.
Patent Literature 3 discloses that CaSi2 is reacted with an acid to synthesize a layered polysilane, and a nano silicon material from which hydrogen is detached is produced by heating the layered polysilane at 300° C. or higher, and that a lithium ion secondary battery including the nano silicon material as an active material exhibits a suitable capacity retention rate.
In addition, in Patent Literature 4, the present inventors have reported that an alloy composed of silicon, calcium, and copper was produced and a silicon material was produced by using the alloy as a raw material.